diff -r 4eeed820fd3a -r ae8063127e95 svghmi/svghmi.py
--- a/svghmi/svghmi.py	Thu Mar 19 19:23:56 2020 +0100
+++ b/svghmi/svghmi.py	Fri Mar 20 10:00:59 2020 +0100
@@ -55,7 +55,7 @@
             self.vartype = vartype
             self.cpath = cpath
 
-        if nodetype in ["HMI_NODE", "HMI_ROOT"]:
+        if nodetype in ["HMI_NODE"]:
             self.children = []
 
     def pprint(self, indent = 0):
@@ -136,7 +136,8 @@
 
 on_hmitree_update = None
 
-SPECIAL_NODES = [("heartbeat", "HMI_INT")]
+SPECIAL_NODES = [("HMI_ROOT", "HMI_NODE"),
+                 ("heartbeat", "HMI_INT")]
                  # ("current_page", "HMI_STRING")])
 
 class SVGHMILibrary(POULibrary):
@@ -183,7 +184,18 @@
         # Filter known HMI types
         hmi_types_instances = [v for v in varlist if v["derived"] in HMI_TYPES]
 
-        hmi_tree_root = HMITreeNode(None, "/", "HMI_ROOT")
+        hmi_tree_root = None
+
+        # take first HMI_NODE (placed as special node), make it root
+        for i,v in enumerate(hmi_types_instances):
+            path = v["IEC_path"].split(".")
+            derived = v["derived"]
+            if derived == "HMI_NODE" and ['CONFIG', 'HEARTBEAT'] :
+                hmi_tree_root = HMITreeNode(path, "", derived, v["type"], v["vartype"], v["C_path"])
+                hmi_types_instances.pop(i)
+                break
+
+        assert(hmi_tree_root is not None)
 
         # deduce HMI tree from PLC HMI_* instances
         for v in hmi_types_instances:
@@ -444,12 +456,6 @@
         return res
 
     def CTNGenerate_C(self, buildpath, locations):
-        """
-        Return C code generated by iec2c compiler
-        when _generate_softPLC have been called
-        @param locations: ignored
-        @return: [(C_file_name, CFLAGS),...] , LDFLAGS_TO_APPEND
-        """
 
         location_str = "_".join(map(str, self.GetCurrentLocation()))
         view_name = self.BaseParams.getName()